464 
PACIFIC SCIENCE, Vol. XV, July 1961 
Fig. 1. Araiophos gracilis, holotype, standard length 34 mm. 
moderate, oblique; edge of premaxillary straight, 
its angle oblique; toothed edge of maxillary 
slightly convex, reaching beyond middle of eye 
but not as far as its posterior margin. Premaxil- 
lary about half as long as toothed portion of 
maxillary. Angle, of preopercle almost vertical. 
All teeth minute, not numerous, uniserial in up- 
per jaw; lower jaw with an outer row of 3-4 
teeth anteriorly. Presence or absence of teeth on 
vomer, palatines, pterygoids, and tongue not de- 
terminable. Gill rakers on first arch 15 + 3 = 18 
( 1 specimen ) , 2 in angle. Minute ( micro- 
scopic) clusters of spines on inner edge of first 
gill arch. Presence or absence of pseudobranch- 
iae not determinable. No evidence of scales. 
Anus about half-way between ventral bases and 
anal origin or slightly nearer the former. Head 
and trunk about equal in length to tail or 
slightly shorter. Origin of dorsal fin well behind 
middle of body length. Anal origin and ventral 
bases well ahead of dorsal origin. Adipose fin 
present. ORB 1, in front of eye, close to pre- 
maxillary. OP 1 (lower posterior), level with 
end of maxillary. SO absent. BR (6). No addi- 
tional photophores on head. Body with a single 
row of photophores; photophores present on 
isthmus. IV ( 2 ) on isthmus, + (3) + 4+ (2) 
= 11. vav (4-5). ac (2) + 3-4 + (2) = 
7-8. IC 22-23. No additional photophores and 
no luminous tissue on body as far as known. 
Fin rays: dorsal 13-14, anal 28-29, pectoral 
(15?) 16-17, ventral 6. Branchiostegal rays 8, 
no spines at bases. Number of vertebrae un- 
known. 
Araiophos differs distinctly from all other 
maurolicid genera in the reduced number of 
photophores. Only in the BR count of 6 and the 
vav count of 4 or 5 is it similar to others ( Val- 
enciennellus Jordan and Evermann also has 4 
or 5 VAV and several genera have 5 ) . The small 
number of photophores might be a juvenile 
character and the absence of photophores be- 
tween the isthmus and the posterior end of the 
pectoral base (where in some species they are 
known to develop late), the absence of 2 of the 
OP, and the small size of the ORB, give sup- 
port to the possibility that all of the specimens 
studied are young. On the other hand, although 
the specimens range in standard length from a 
little over 21 mm. to 34 mm., the number and 
relative size of the photophores are identical in 
all. If more were to develop, on the body at 
least, one would expect to find the smallest spec- 
imen differing somewhat from the largest. The 
presence of gonads is also significant and the 
obvious implication is that Araiophos provides 
another example of neoteny among fishes. Even 
were the specimens still juvenile they could not 
be shown to belong to any known genus. Only 
in Maurolicus Cocco is the dorsal fin situated so 
far behind the middle of the body length; and 
the Hawaiian specimens cannot belong to Mau- 
rolicus, in which the developmental stages are 
well known and which has acquired all of the 
meristic characters of the adult at a length of 
about 20 mm. Nor is it likely that the Hawaiian 
specimens represent a metamorphosis stage of 
some known genus; as far as we know the de- 
velopment of maurolicid genera is direct and 
none are known to undergo a metamorphosis 
